Generally true, but if the professor in this context was not a moron, he probably mentioned at the start of the class that he would be forcing a change to requirements part way through the course. Ideally, he would've specified what kind of changes this would be, in order for the students to account for that in their design. I think it's likely this happened, but the student was lacking so much experience he didn't understand that hint or what he needed to do in the design in order to later swap parameters more easily. I'm going to withhold judgement on this professor having only heard a biased account. It could've been a very good assignment, now being told from the perspective of a mediocre student.